This show-stopping main course, served with celeriac purée and anchovy butter, is perfect for a special occasion
For the butter:
75g (2¾oz) butter, not fridge-cold but firmish
10 anchovies, drained of oil and very finely chopped
½ garlic clove, crushed
1 tbsp finely chopped parsley
For the puree:
about 900g (2lb) celeriac
1 litre (1¾ pints) milk
100ml (3½fl oz) chicken stock
40g (1½oz) butter, melted
4 tbsp cream
squeeze lemon (optional)
For the beef:
1.8kg (4lb) fillet of beef
1 tbsp olive oil or beef dripping
Pound the butter in a mortar and pestle until softened, then pound in the anchovies and garlic and stir in the parsley. Put in the fridge and, when firm enough, form into a fat sausage shape and wrap in clingfilm or greaseproof paper. Chill.
Peel the celeriac and chop into cubes. Put in a pan with the milk, bring to just under the boil, then reduce the heat and simmer for 20 minutes, or until the cubes are tender. Drain, reserving the milk.
Purée the celeriac with the chicken stock, butter, cream and some seasoning, adding as much of the milk as you need to make a smooth purée (not soup). Check for seasoning. You might want a squeeze of lemon just to brighten the flavours and pull everything together. Set aside.
Preheat the oven to 220°C/425°F/gas mark 7.
Season the beef really well all over and heat the oil or dripping in a large frying-pan. When the fat is smoking, add the beef to the pan and colour the outside really well, turning the meat over as it browns. Transfer to a roasting-tin and cook for 10 minutes. Turn down the heat to 200°C/400°F/gas mark 6 and cook for 20 minutes.
Pour any juices from the roast into a jug and cover the beef with foil. Insulate well and leave to rest for 15 minutes.
Reheat the purée. Slice the beef and serve with a round of the butter melting over the meat. Drizzle over the warmed beef juices if there are any. Some cubes of potato roasted in olive oil or sautéed are good too, as is warm roast beetroot.